Electric submersible pumps installed in-line on well tubing strings present problems in well monitoring and treatment. Wire line tools, coiled tubing and other devices cannot be lowered to the production interval below the pump due to the presence of the pump/motor assembly in the well bore.
In order to permit passage of wire line tools and the like, Y-shaped bypass pump assemblies have been developed. However, these bypass assemblies can only be accommodated in well casings that are substantially larger than the standard oil casings presently employed in oil fields throughout the world. The cost of retrofitting a well with the 95/8" casing required to install a Y-shaped bypass assembly is estimated to be approximately one million dollars.
It is therefore one principal object of this invention to provide an electric submersible pump that can be installed in existing well bores and that will permit the passage of wire line logging tools and other devices that are required to monitor and maintain the well tubing and casing string.
It is another object of the invention to provide an electric submersible pump that can be installed in-line with the production tubing and that can be coupled to standard sections of tubing pipe.
Another object of the invention is to provide an electric submersible pump that is of durable construction, that will provide a long service life with minimum maintenance and that is relatively simple and economical to install in new and existing well casings.
Another object of the invention is to provide a method and apparatus for use in wells in which a submersible electric motor and pump assembly are installed on a hollow shaft that is axially aligned with the pipe through which the fluid drawn from the well passes, where the hollow shaft will freely permit the passage of devices lowered from a position above the pump assembly to the production interval below the pump.